Howard Vollum (pronounced VAH-lum) was the key figure in the development of the oscilloscope as we know it today. Following World War Two, Vollum worked with a few friends to found Tektronix, and the small group of veterans set about manufacturing oscilloscopes. They saw the need for a better instrument. Prewar oscilloscopes could measure only one-shot or continuous events. Howard, who had built cathode ray tube oscilloscopes since his youth, advanced the idea of triggering.
Electronic waveforms have always been displayed along a horizontal X-axis corresponding to time. By convention, consecutive time periods begin at the left side and progress to the right, probably because we are accustomed to reading left to right. For repetitive waveforms and without triggering, this would work fine if the screen could be indefinitely wide. But this is not possible because of cathode-ray-tube constraints including deflection voltage limitations. The electron beam must return to the left side of the screen and do a retrace. It would be unlikely that successive traces would precisely coincide (they were not synchronized with the signal they were trying to represent), so repetitive signals displayed on early oscilloscopes appeared as a meaningless blur of light or at best a horizontally rolling graphic representation.
Research and development during the Second World War, notably in radar systems for the defense of England against Axis bombing raids, had given rise to the concept of triggering. Then the Tektronix crew, in 1947, succeeded in making available a true triggered-sweep oscilloscope. In response to a predetermined voltage level in the signal under investigation, the oscilloscope circuitry would cause the electron beam to return to the left side of the screen and initiate a new trace, exactly coinciding with the previous cycle. The distracting return beam was blanked out as in television protocol, resulting in a clean display.
The first Tektronix model 501 incorporated triggered sweep and it was far more sophisticated than competing instruments. Still, it was large and quite heavy. The Model 511 was essentially the same instrument, redesigned to make it lighter and more compact. Without the sloping top, it was user-friendly and still affordable.
The great post-war electronics boom included a rapid rise in television broadcast infrastructure. Before long there was a TV in almost every home. Much more complex than radio, the TV required use of an oscilloscope for isolating faults to a section, stage and component. Technicians learned to inject signals at various points and, using the oscilloscope, follow the waveform downstream until it disappeared or exhibited distortion. Available service information included schematics with graphics depicting correct waveforms at selected outputs.
Tektronix, largely inspired by Howard, led the way in oscilloscope innovation during the post-war period and beyond. The Oregon facility grew, always maintaining an informal but strong work ethic inspired by Howard and other key figures, including Jack Murdock, partner from the start, who perished in a tragic airplane crash in 1971.
Howard lived until 1986. Through hard work and persistence he amassed a fortune, which he and his wife, Jean, distributed through a charitable foundation, benefiting biomedical research and other educational projects in Oregon and beyond.
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